Last week a workshop at the International Horticultural Congress in Lisbon, Portugal featured a series of speakers known for their work in transgenic  technology.  I’ll summarize these in the next few posts.  Today’s post addresses an important question- why are there few horticultural (basically non-agronomic fruits and vegetables) transgenic crops available, at least relative to corn, soy and other huge agronomic crops?  These are the capsules of flavor and nutrition truly necessary in a diverse diet, yet they suffer tremendous challenges to production and distribution.  Transgenic technologies could deliver great benefits.

The issue was approached by Dr. Ralph Scorza from the USDA Appalachian Fruit Research Station. I’ve known of Dr. Scorza’s outstanding work for almost two decades.  Years ago he sought a solution to the plum pox virus (PPV), the causative agent of a devastating disease called Sharka. The disease affects stone fruits (peaches, apricots, others) and can destroy whole orchards and decimate natural populations.  While breeding solutions are being pursued with timelines measured in decades, PPV can now be mitigated with Scorza’s solution by grafting a stonefruit scion to the transgenic rootstock.  Works like a charm, and the fruit are not transgenic.

The solution was introduction of a gene encoding the coat protein of PPV.  When overexpressed in plums (because they are routinely transformed in the Scorza Lab), the plant became immune to the disease, almost like a vaccination.  While this was interesting science it was not viewed as an application, that is until PPV was identified in the United States.  While the disease was successfully controlled with quarantine, the development of PPV-resistant plums (a cultivar known as “Honeysweet”) was initiated as a solution in future outbreaks.

Years later in 2010, the Honeysweet cultivar has found approval.  It is a true minority, as very few horticultural crops are ever approved, reserving much of the focus for major agronomical crops like soy and corn.  To date, only 6% of de-regulated crops are horticultural and only 1% had viable commercial potential.  Of that, 0.2 were crops other than tomato and potato. Therein lies the question, why are transgenic technologies not approved (or even pursued) in fruits and vegetables?

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